Abstract: [Objective] To assess the characteristics and variation of spatial heterogeneity of Stipa breviflora as constructive species in desert steppe under different grazing intensities. [Method] The constructive species of Stipa breviflora was taken as the research object. The semi-variance function, Kriging interpolation and multi-fractal dimension were used to assess its spatial heterogeneity.[Result] Under different grazing intensities, the mean population density of Stipa breviflora was heavy-grazing area （HG） > no-grazing area （CK） > moderate-grazing area （MG）; Stipa breviflora population had multi-fractal characteristics; the spatial distribution of Stipa breviflora varied under different grazing intensities; the structure ratio （C/C₀+C） of CK was the largest, followed by HG, and both of them were greater than 75%, indicating that CK and HG had strong spatial autocorrelation; the structure ratio （C/C₀+C） of MG was the lowest, which ranged from 25% to 75%, indicating that MG had moderate spatial autocorrelation; structural factors were the main causes of spatial variation of Stipa breviflora.[Conclusion] Heavy-grazing increases the population density of Stipa breviflora, while moderate-grazing decreases the population density of Stipa breviflora due to the low-intensity feeding and trampling from livestock; under different grazing intensities, structural factors mainly contribute to the spatial heterogeneity of Stipa breviflora; the Stipa breviflora population in CK has the most complex spatial distribution and strong spatial heterogeneity.

Key words: grazing intensity, Stipa breviflora, spatial heterogeneity, desert steppe